Conductor for the transmission of electrical energy and method of producing the same



CTRICAL ENERGY SAME . Dec. 25, 1926.

A. F. BANDUR TRANSMISSION OF OD CONDUCTOR, FOR THE I AND METH OF PRODUCING Filed Dec. 24, 1925 Patented Dec. 25:16:28.

UNI D STATES PATENT OFFICE.

ADOLPH FRANCIS BANDUBQOFBERWYN, ILLINOIS, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OI NEW YORK, N. Y., A CORPORATION OF NEW Yonx. I

' connuc'ron r012. THE rmsmssron or ELECTRICAL ENERGY AND mnrnon or s rnonucmo .rnn sans.

Appllcationiflled December 24, 1923. Serial No. 682,417.

, This invention relates to conductors for the transmission of electrical energy and methods of producing the same, and nioreparticularly to composite signalling conductors 5' having an external layer ofmaterial of high permeability for the purpose of increasing the inductance'of the conductor, the electrical characteristics of the material being determined to some extent by heat treatment.

One manner of increasing the inductance of a conductor employed for the transmission of alternating current is to wrap the con- 7 ductor spirally with a layer of wire or tape of magnetic material This method is known in theart as continuous inductiveloading as distinguished from lump loading-by means of coils distributed along the conductor. Until recently iron has been considered to be-the A only material available for i'continuous loading. It has been discovered, however, that a more suitable material maybe roduced in the formiof an alloy of nicke and iron.

- When these two metals are inpr'oper pro-v portions and. the alloy is given proper heat treatment, armaterial having veryhigh per meability at low magnetizing forces is ob tained. For a full disclosure of the metallurgical and electrical characteristics of this 9.110 and its heat treatment, reference is ma e to the patents of Gustaf W. Elmen,

1,586,884,. issued June 1, 1926; Oliver E.

Buckley, 1,586,874, issued June 1, 1926, and

Gustaf W. Elmen, 1,586,887, issued June 1,

ent 1,537,575, issued May 12, 1925, in which the loading material is preferably applied in 40 the form of a helical tape wrap around the conductor and subjected to t e requisite heat treatment while wrapped thereon.

It has been found that when this alloy loadii g material is subjected to stresses or strainsl'that the permeability thereof is materially lowered and that in some cases these deleterious stresses or strains occur durin the heat treatment of the loading materidl site conductor.

An object of this invention is to provide a ductor of the type above described.

One method of applying the alloy loading material above described to a composite s ig-' nalling conductor is that described in Pat and are due to the construction ofthe 00m composite electrical conductor so designed that when it has been wrapped with a mag- Another object of the invention is to pro vide a method of making a composite con- Other objects and advantages of the invention will appear from the following detailed;

description and will be particularly pointe outin the appended claims.

In the accompanying drawings,

Fig. 1 is a fragmentary side elevation of a composite conductor made in accordance with the invention, part of the alloy loading tape being cut away to more clearly show the I conductor;

Fig. 2 is. a vertical sectional view of the composite conductor before the copper tapes have been rolled, and

Figs. 3 and 4 are vertical sectional views" of the conductor shown in Fig. 1 before and afterthe heat treatment of the alloy loading tape, respectively. The construction of a composite conductor made in accordance -with the invention will be clearly understood by a description of the method of making the same. i

A plurality of soft copper tapes 10, preferably. sixin number, are curved on a radius considerably shorter than the radius of the central copper wire 11 and are then wrapped around the said wire 11 so that they occupy the positions as shown in Fig. 2. The tapes 10 may be curved and then wrapped around the wire 11 by any suitable means. The apparatus disclosed in Patent 1,651,024, November29, 1927, is well adapted for this purpose. After the tapes 10 are wrapped around the conductor 11, they are rolled down into closer contact with the said conductor, as shown in Fig. 3. Any suitable'means may be employed to perform the rolling operation. A roller or rollers rotatable around the composite conductor may be used to advantage for this purpose. It is important, for reasons which will hereinafter appear, that not too great a pressure is applied'to the tapes lO'during the rolling operation, so that after the tapes have been rolled they will not tightly hug the central conductor 11 but their central portions will still be slightly spaced from the central conductor 11, as shown in Fim '3.

After the tapes 10 have been subjected to the rolling operation above described, the composite conductor is ready to receive the alloy loading material which is applied in the form of a tape 1:2 and which is wrapped around the composite conductor by any suitable means, but preferably by the method and apparatus described in Patent 1,565,652, to F. S. Kochendorfer et 211.. issued December 15, 1925, to form the completed conductor as shown in Fig. 1.

Due to the concave shape of the tapes 10, the composite conductor presents a smooth outer surface, which is free of sharp edges or ridges, so that when the tape loading material 12 is wrapped therearound it may assume a substantially true circular spiral as viewed in Fig. 4 and not be subjected to undue strains at any point, as would be the result should the composite conductor present ridges or sharp edges over which the tape loading would necessarily be bent during the wrapping operation thereof.

The central copper conductor 11 and the tapes 10, have a higher coellicient of elongation than the alloy tape 12. Measuring a plurality of samples of the composite conductor and the alloy tape, the former has been found to have a COGffiClBIlt of elongation from 11 to 53 per cent higher than that of the alloy tape. Due to this difference, unless precautions are .taken to prevent it, the natural tendency of the composite conductor to expand more rapidly than the alloy tape will cause the latter to be subjected to deleterious stresses and strains during the heat treatment thereof. The difficulty of obviating these stresses and strains is increased, since during the heat treatment of the loaded conductor it is raised from room temperature to 1530 F. during approximately 47 seconds time.

Where a composite conductor is made as above described, during the heat treatment of the alloy loading material applied thereto, in which the composite conductor and load ing material are subjected to a high temperature in a furnace, the copper tapes 10 will expand more rapidly than the alloy loading tape 12. The more rapid elon ation of the tapes 10, however, will be absor ed by a fiattening of the tapes so that they are brought into closer contact with the central wire 11 and do not subject the tape loading material to the undue strains which would occur were no space afforded to receive the differential of expansion between the tapes 10 and the loading tape 12.

Also due to the smooth outer surface presented by the tapes 10, these tapes and the alloy loading tape 12 are free to slip relatively the said tape being concave in cross section i 7 longitudinally of the tape. and a magnetic loading material wrapped around said composite strand and making only a line contact with said tape, said loading material requiring heat treatment to give ita. desired electrical characteristic.

2. A loaded signalling conductor coi'nyn'ising a composite copper strand consisting of a copper wire, a plurality of copper tapes stranded thereon, said tapes having a concave cross section longitudinally of the tape with only their edges in close contact with the surface of the copper wire, and a metallic loading material wrapped around said composite strand, said loading material requiring heat treatment to give it a desired electrical characteristic.

3. A loaded signalling conductor comprising a composite metallic strand consisting of a metallic wire wrapped with metallic tape. the said tape having an arcuate cross section of a shorter radius than the radius of the wire, and a magnetic loading material wrapped around said composite strand, said loading materialrequiring heat treatment to give it a desired electrical characteristic.

4. A loaded signalling conductor comprising a composite metallic strand consisting of a metallic wire wrapped with metallic tape, the said tape having an arcuate cross section, said are being of a shorter radius than the radius of the wire and the said tape positioned so that the edges thereof are in close contact with the surface of the wire, and a magnetic loading material wrapped around 7 said composite strand, said loading material requiring heat treatment to give it a desired electrical characteristic.

5. A loaded signalling conductor comprising a composite copper strand consisting of copper wire wrapped with copper tape, said tzppe having an arcuate cross section, the are 0 which has a shorter radius than the radius of the wire, the said tape so positioned that the edges thereof are in close contact with the surface of the wire, and a magnetic loading material comprisng a metallic tape wrapped around said composite strand, said tape requiring heat treatment to give it a desired electrical characteristic.

(3. A method of loading a signalling conductor with magnetic material which re- 1% quires heat treatment to give it a desired electrical characteristic, consisting in forming a metallic tape so that it has an arcuate cross section, wrapping the said tape around a metallic wire to form a composite strand,

Inn

section, wrapping the said tape around a met'allic wire in such manner that the edges of the tape are in close" contact with the surface of the wire to form a composite conductor, and then wrapping the loading material around said composite conductor.

8. A' method of loading asignalling conductor with magnetic material which requires heat treatment to give it a desired electricalcharacteristic, which consists in forming a copper tape so thatit hasan arcuate cross section, wrapping the said tape around a copper wire in such manner thatthe edges of the tape are in close contact with the surface of the wire, rolling the tapeso that it more nearly embraces the wire, and then wrapping the loading material around the said tape. p

9. A method of loading a signalling conductor with magnetic material which requiresheat treatment to give it a. desired electrical characteristic,consisting in forming a metallic tape so that itfhas an arcuate cross section of a shorter radius than the metallic wire around which thetape is to be wrapped, wrapping the said ta pe around the 35. wire, and then wrapping thev loading material around said tape. 1

I 10. A method of loadinga'signalling conductor with magnetic material whiclirequires heat treatment to give it a desired electrical characteristic, consisting informing a. metall'ic tape so that it has an arcuate'cross section of a shorter radius than the metallic wire around which the tape is to be Wrapped,

wrapping the tape around the wire in such manner that the edges thereof are in close contact'with the surface of the wire, and then wrapping, the loading material around said composite strand.

11. An electrical signalling conductorcomprising a metallic core, a metallic member having pro ect1ng portions surrounding said.

-core, and a magnetic loading material wrapped'around said metallic material and engaging the projecting portions thereof.

12. A loaded signalling conductor comprising a compositemetallie strand consisting of a metallic core wrapped with a metallic conductor, the said conductor having an arcuate cross-section of a shorter radius than that of the core, and a magnetic loading material wrapped around saidcomposite strand.

13. A loaded signalling conductor comprising a composite metallic strand, consisting of a metallic wire encircled by metallic elements forming hollowsand' ridges, and a magnetic loading material wrappedaround .65 said composite strand and spaced from said 7 metallic elements at the hollows formed thereby.

In witness whereof, I hereunto subscribe my name this 17 day of December A. 11,1923.

ADOLPH' m nors BANDUR. 

